A transsexual phony medic who allegedly injected patients with a substance that left them with life-threatening infections is still at large, police said yesterday.

Two other suspects are already under arrest in the case – Iris and Eliezar Fernandez, who ran beauty clinics out of their homes in Queens and Manhattan.

Now police are looking for someone known by the name “Natasha,” who posed with the Fernandezes as a plastic surgeon and is wanted for questioning in connection with a rash of horrific skin sores that overcame clients, said Police Commissioner Ray Kelly.

One of Natasha’s clients needed a double mastectomy after a breast enlargement went awry, Kelly said.

Natasha preyed on fellow transgenders and low-income Latin American immigrants at a clandestine clinic in Washington Heights, cops said.

Police are having trouble locating Natasha because some of the faux medic’s clients are protecting their beauty guru, despite the serious injuries they suffered, law-enforcement sources said.

Natasha, along with the Fernandezes, caused a mini-outbreak by injecting clients with a Botox-like wrinkle-filler smuggled from South America, authorities said.

Of the nine people infected, five of the victims are still hospitalized and all are permanently disfigured, authorities said.

The Fernandezes were charged Thursday with assault and various other crimes and are being held without bail. The couple face up to 25 years in prison.

Iris Fernandez, 49, a dentist in her native Venezuela, and her husband, Eliezar, 53, confessed to cops that they knew it was wrong to pose as doctors.

Authorities said the Fernandezes and Natasha injected their patients with a hyaluronic acid called Hyacell, which may have caused the infections.

Hyacell, distributed by Miami-based Propharma, has not been approved for use in the United States.

The substance is made from extracts of rooster combs and is marketed to fill wrinkles and plump sagging skin, according to Propharma’s Web site.

Iris Fernandez – known to her patients as “Dr. Iris” – told police she blamed the infections on a contaminated batch of drugs.

But it appears the phony trio misused the product – pumping large quantities of the beauty cure into hands, thighs, faces and breasts, physicians familiar with such products said.